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Cell membrane

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Saad Al-mohnna

This document summarizes mechanisms of transport across the cell membrane. It discusses passive transport mechanisms like diffusion and facilitated diffusion, as well as active transport mechanisms like pumps, endocytosis, and exocytosis. It describes channel proteins, carrier proteins, and osmosis. Larger molecules enter and exit cells through endocytosis and exocytosis. There are modifications to the cell membrane including the apical, lateral, and basal surfaces, which increase surface area and facilitate transport and cell adhesion.

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Present by Saad Sami Almuhanna
What are the different Mechanisms responsible of transport? How the large molecules transport out from and into the cell ? What are the Modifications, their functions, examples ?
Passive transport Active transport
1.Diffusion 2. Facilitated diffusion 3. Osmosis
Movement from high concentration to low concentration.
Channel proteins Provide corridors that allow a specific molecule or ion to cross the membrane. Carrier proteins Undergo a subtle change in shape that translocate the salute-binding site across the membrane.
The movement of water across a semi permeable membrane. Osmosis is the movement of water (red dots) through a semipermeable membrane to a higher concentration of solutes (blue dots).
Process that moves materials across the plasma membrane Requires energy from the cell in the form of ATP Materials move against the concentration gradient: low concentration high concentration 3 Kinds: Pumps, Endocytosis, and Exocytosis
1. An ATP molecule breaks down into ADP, releasing a phosphate group and a whole lot of energy. 2. The phosphate group attaches to a protein pump, causing it to change its shape so that it can move a small molecule or ion across the plasma membrane. 3. The protein changes shape again so that the molecule can be released on the other side. There are many types of carrier proteins and they only carry specific molecules across the plasma membrane.
Larger molecules cannot fit. Because they are too big so they enter the cell by endocytosis and go out by exocytosis
Larger materials transport into the cell it is includes three slightly different processes: Endocytosis:- 1. Phagocytosis: cell eating 2. Pinocytosis: cell drinking 3. Receptor mediated endocytosis
1. Phagocytosis:- endocytosis of solid particles. - cell engulfs particle with pseudopodia and pinches off a food vacuole - vacuole fuses with a lysosome containing hydrolytic enzymes that will digest the particle 2. pinocytosis:- fluid droplets of extracellular fluid are incorporated into small vesicles the process is not discriminating. the cell takes in all solutes dissolved in the droplet 3. receptor-mediated endocytosis:- - cells have receptors for certain molecules on their surface. when these receptors encounter t molecule, they bind tightly to it. the complex of the molecule and its receptor is then engulfed by endocytosis. - a molecule that binds to specific receptor site of another molecule is called a ligand.
Exocytosis:- The movement of material out of the cell via membranous vesicles
Modification apical lateral basal
1. Apical surface its tissue of cell membrane on toward the lumen, there are many examples of apical - stereocilia - cilia - flagella - microvilli
Its function is increase the cells surface area, facilitating the movement of molecules into and out to the cell Its can be found in the lining of the epididymis
Its function is Its can be found in trapping the materials to protect them the lining of the trachea ( windpipe)
Its function is Its can be found in reflecting cytoplasmic movement that will increase the total surface area of cells kidney and intestines
Its function is Its can be found in it concerned with movement in some certain eukaryotes EX. sperms in humans
2.lateral it is a kind of protein which joins between adjacent cells within epithelium these proteins have four types of junction: tight junction gap junction adherens junction desmosome
to form seal that prevents the flow of materials between epithelial cells in either direction. - help prevent the integral membrane proteins of the apical surface from being transferred epithelial cells in general, brain cells Function: Examples
permit the rapid exchange between cells of molecules with small diameters Function: Examples they are relevant in signal transfers in the brain
unction provide strong mechanical attachments between adjacent cells (provide for firm adhesion of one cell to its neighbors ) Function: Examples present in narrow bands connecting adjacent cells or discrete patches holding the cells together
desmosome provide firm adhesion among the cells Function: Examples Skin cells
3- Basal its a friction of the plasma membrane at the basal side, which faces the underlying connective tissue Example of Basal polarity Basal lamina
polarity in cells, polarity refers to the asymmetric organization of different aspects of the cell including the cell surface, intracellular organelles and the cytoskeleton
Basal Lamina Basal Lamina acts as base where the cells in the body can grow. It links cells together and underlies connective tissue.
Cell membrane

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Cell membrane

  • 1. Present by Saad Sami Almuhanna
  • 2. What are the different Mechanisms responsible of transport? How the large molecules transport out from and into the cell ? What are the Modifications, their functions, examples ?
  • 3. Passive transport Active transport
  • 5. Movement from high concentration to low concentration.
  • 6. Channel proteins Provide corridors that allow a specific molecule or ion to cross the membrane. Carrier proteins Undergo a subtle change in shape that translocate the salute-binding site across the membrane.
  • 7. The movement of water across a semi permeable membrane. Osmosis is the movement of water (red dots) through a semipermeable membrane to a higher concentration of solutes (blue dots).
  • 8. Process that moves materials across the plasma membrane Requires energy from the cell in the form of ATP Materials move against the concentration gradient: low concentration high concentration 3 Kinds: Pumps, Endocytosis, and Exocytosis
  • 9. 1. An ATP molecule breaks down into ADP, releasing a phosphate group and a whole lot of energy. 2. The phosphate group attaches to a protein pump, causing it to change its shape so that it can move a small molecule or ion across the plasma membrane. 3. The protein changes shape again so that the molecule can be released on the other side. There are many types of carrier proteins and they only carry specific molecules across the plasma membrane.
  • 10. Larger molecules cannot fit. Because they are too big so they enter the cell by endocytosis and go out by exocytosis
  • 11. Larger materials transport into the cell it is includes three slightly different processes: Endocytosis:- 1. Phagocytosis: cell eating 2. Pinocytosis: cell drinking 3. Receptor mediated endocytosis
  • 12. 1. Phagocytosis:- endocytosis of solid particles. - cell engulfs particle with pseudopodia and pinches off a food vacuole - vacuole fuses with a lysosome containing hydrolytic enzymes that will digest the particle 2. pinocytosis:- fluid droplets of extracellular fluid are incorporated into small vesicles the process is not discriminating. the cell takes in all solutes dissolved in the droplet 3. receptor-mediated endocytosis:- - cells have receptors for certain molecules on their surface. when these receptors encounter t molecule, they bind tightly to it. the complex of the molecule and its receptor is then engulfed by endocytosis. - a molecule that binds to specific receptor site of another molecule is called a ligand.
  • 13. Exocytosis:- The movement of material out of the cell via membranous vesicles
  • 15. 1. Apical surface its tissue of cell membrane on toward the lumen, there are many examples of apical - stereocilia - cilia - flagella - microvilli
  • 16. Its function is increase the cells surface area, facilitating the movement of molecules into and out to the cell Its can be found in the lining of the epididymis
  • 17. Its function is Its can be found in trapping the materials to protect them the lining of the trachea ( windpipe)
  • 18. Its function is Its can be found in reflecting cytoplasmic movement that will increase the total surface area of cells kidney and intestines
  • 19. Its function is Its can be found in it concerned with movement in some certain eukaryotes EX. sperms in humans
  • 20. 2.lateral it is a kind of protein which joins between adjacent cells within epithelium these proteins have four types of junction: tight junction gap junction adherens junction desmosome
  • 21. to form seal that prevents the flow of materials between epithelial cells in either direction. - help prevent the integral membrane proteins of the apical surface from being transferred epithelial cells in general, brain cells Function: Examples
  • 22. permit the rapid exchange between cells of molecules with small diameters Function: Examples they are relevant in signal transfers in the brain
  • 23. unction provide strong mechanical attachments between adjacent cells (provide for firm adhesion of one cell to its neighbors ) Function: Examples present in narrow bands connecting adjacent cells or discrete patches holding the cells together
  • 24. desmosome provide firm adhesion among the cells Function: Examples Skin cells
  • 25. 3- Basal its a friction of the plasma membrane at the basal side, which faces the underlying connective tissue Example of Basal polarity Basal lamina
  • 26. polarity in cells, polarity refers to the asymmetric organization of different aspects of the cell including the cell surface, intracellular organelles and the cytoskeleton
  • 27. Basal Lamina Basal Lamina acts as base where the cells in the body can grow. It links cells together and underlies connective tissue.